JPH0687699A - Aluminum borate whisker and metal-based composite material containing relevant whisker as reinforcing material - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the performance of aluminum borate whiskers and reduce the variation in strength of the composite material using them. [Structure] The aluminum borate whisker 10 has a Si content of 150 ppm or less. Further, the composite material uses aluminum borate whiskers having a Si content of 150 ppm or less as a reinforcing material and a light alloy such as an aluminum alloy as a matrix.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material, and more particularly to an aluminum borate whisker and a metal matrix composite material containing the whisker as a reinforcing material.

[0002]

2. Description of the Related Art As one of Al-based composite materials, for example, "Interface in Whisker-Reinforced Aluminum-based Composite Material" distributed by the Wetting Subcommittee Committee of the Composite Materials Subcommittee of Japan Institute of Light Metals on April 23, 1990 As described in the article entitled "Structure", aluminum borate whiskers (alumina-boria whiskers) are used as reinforcements, and A6061 alloy and J
Al-based composite materials having an Al alloy such as IS standard AC8A alloy as a matrix are already known.

9A for aluminum borate whiskers
There are two types represented by l ₂ O ₃ · 2B ₂ O ₃ and 2Al ₂ O ₃ · B ₂ O ₃ , and among these, the aluminum borate whiskers represented by the former chemical formula are strength and elasticity. Rate, heat resistance and chemical resistance, it is an excellent whisker as a reinforcing material for composite materials. Further, since aluminum borate whiskers are extremely inexpensive reinforcing materials, aluminum borate whisker reinforced Al-based composite materials provide a much cheaper composite material than, for example, a composite material using SiC whiskers as a reinforcing material. Obtainable.

[0004]

However, in the case of a composite material containing aluminum borate whiskers as a reinforcing material and Al alloy as a matrix, the strength of the composite material depends on the kind and amount of impurities unavoidably contained in the whiskers. There is a problem that the variation of is relatively large.

The inventor of the present invention has made detailed experimental investigations on the cause of the relatively large variation in the strength of the aluminum borate whisker reinforced metal matrix composite material, and as a result, Si is present at the starting point of the fracture of the composite material. , It was clarified that the presence of Si has some influence on the variation in the strength of the composite material, and the variation in the strength of the composite material was reduced by reducing the Si content of aluminum borate whiskers to a predetermined value or less. Found to get.

The present invention is based on the knowledge obtained as a result of an experimental study conducted by the inventor of the present application, and an aluminum borate whisker capable of reducing variation in strength of a composite material and a high-performance aluminum borate without variation in strength. It is an object to provide an aluminum borate whisker reinforced metal matrix composite material.

[0007]

According to the present invention, the above object is to provide an aluminum borate whisker having a Si content of 150 ppm or less, and boric acid having a Si content of 150 ppm or less. This is achieved by a metal matrix composite material having aluminum whiskers as a reinforcing material and a light alloy as a matrix.

[0008]

According to the whisker of the present invention, the Si content is 15
Since it is suppressed to 0 ppm or less, variations in the strength of the whiskers themselves are reduced, which reduces variations in the strength of the composite material using aluminum borate whiskers as a reinforcing material.

Further, according to the composite material of the present invention, since the Si content is 150 ppm or less and the aluminum borate whiskers having no variation in strength are used as the reinforcing material,
An aluminum borate whisker reinforced metal matrix composite material having less strength variation than before can be obtained.

[0010]

[Supplementary Explanation of Means for Solving the Problem] According to the result of the experimental research conducted by the inventor of the present application, commercially available aluminum borate whiskers contain 200 to 220 ppm of Si, and the whiskers contain Si. When the amount is 150 ppm or less, particularly 100 ppm or less, the variation in strength of the composite material can be significantly reduced. Therefore, according to one embodiment of the present invention, the Si content of the aluminum borate whiskers is set to 100 ppm or less.

Further, according to the result of the experimental research conducted by the inventor of the present application, it is found that the commercially available aluminum borate whiskers have a viscosity of 10%.
It contains more than ppm of Cl, the presence of Cl affects the strength of the whisker, the Cl content of the whisker is 8ppm or less,
Especially when the content is suppressed to 6 ppm or less, the strength of the whisker and the composite material is improved. Therefore, according to one embodiment of the present invention, the aluminum borate whisker has a Cl content of 8 ppm.
Below, it is preferably set to 6 ppm.

[0012]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Example 1 First, aluminum borate whiskers having Si contents set to 100, 150 and 200 ppm (“Arborex G” manufactured by Shikoku Chemicals Co., Ltd., whisker diameter 0.5 to 1 μm)
, Whisker length 10-30μm, Cl content 10ppm)
As shown in FIG. 1, aluminum borate whiskers 10 are put into distilled water 12, the distilled water and whiskers are stirred by a propeller 14 until the whiskers are sufficiently defibrated, and then the whiskers are molded and treated. A compact having a size of 100 × 38 × 16 mm is formed by transferring it into a tool and performing compression molding, and the compact is placed together with a jig in a freezer kept at −50 ° C. It was kept until the water was sufficiently frozen.

Next, the molded body was taken out from the jig, and as shown in FIG. 2, the inner dimension was 38 × 16 mm and the length was 140 mm, and the weight 16 was opened at both ends and the weight 16 was formed at one end. Was integrally provided in a case 18 made of stainless steel (JIS standard SUS304) with the molded body 20 formed as described above. Next, the molded body was heated by a heater together with the case to sufficiently dry the molded body, thereby forming six molded bodies of aluminum borate whiskers having a whisker volume ratio of 30% for each Si content. .

Next, each molded body is placed in a case at 600 ° C.
After preheating for a period of time, as shown in FIG. 3, the compact 20 is placed in a mold 24 of a high-pressure casting apparatus 22 together with the case, and an Al alloy (Al-4 wt% Cu-1 wt%) at 700 ° C. is placed in the mold.
% Si) molten metal 26 was poured, and the molten metal was pressurized by a plunger 28 fitted in a mold at a pressure of about 1000 kgf / cm ² , and the pressurized state was maintained until the molten metal was completely solidified. After the melt has completely solidified, knockout pin 30
The solidified body is taken out from the mold 24 by means of, and the solidified body is machined to cut out a composite material made of an Al alloy that has been composite reinforced with aluminum borate whiskers.
Heat treatment T6 was applied to the composite material.

Then, a rotary bending fatigue test piece was formed from each composite material, and a rotary bending fatigue test was performed on each test piece at room temperature. The results of these tests are shown in FIG. From FIG. 4, the Si content of aluminum borate whiskers is 150
It is understood that the strength variation of the composite material can be reduced by reducing the content to ppm or less.

Example 2 As a matrix metal, an Al alloy (Al
-5 wt% Cu-0.5 wt% Mg) was used, and a composite material was formed under the same procedure and conditions as in Example 1 except that the whisker volume ratio was set to 25%. ,
T6 heat treatment is applied to each composite material to form a bending test piece from each composite material.
A 3-point bending test was performed at m and room temperature.

The results of these tests are shown in FIG. Figure 5
In the above, the bar graph shows the average value of the test results of the six test pieces, and the upper and lower limits of the error bars show the maximum and minimum values of the test results, respectively. From FIG. 5, even when the composition of the Al alloy as the matrix is different from that of the Al alloy of Example 1, the variation in strength of the composite material is reduced by reducing the Si content of the aluminum borate whiskers to 150 ppm or less. It turns out that you can do it.

Example 3 As a matrix metal, an Al alloy (Al
-5 wt% Cu-0.5 wt% Mg) is used, the Si content and the Cl content of aluminum borate whiskers are set to 100 ppm and 10 ppm, respectively, and the volume ratio of whiskers is 15 (the lower limit of moldability). ) To 50% (every 5%) except that the composite material was formed under the same procedure and conditions as in the case of Example 1, and T was added to each composite material.
6 Heat treatment is applied to form bending test pieces from each composite material.
A three-point bending test was performed on each test piece under the same procedure and conditions as in Example 2.

The results of these tests are shown in FIG. From FIG. 6, it is understood that the volume ratio of the aluminum borate whiskers is preferably 15 to 40% in order to obtain a composite material having excellent strength.

The matrix metal is an Al alloy (Al-5
wt% Cu-1 wt% Si) also in the above-mentioned Example 1
The results showing the same tendency as the results of ~ 3 were obtained.

Although the present invention has been described above in detail with reference to specific embodiments, the present invention is not limited to these embodiments, and various other embodiments within the scope of the present invention. It will be apparent to those skilled in the art that

[0023]

As is clear from the above description, according to the aluminum borate whiskers and the composite material of the present invention, it is possible to reduce variations in the strength of the whiskers themselves as compared with conventional ones, and aluminum borate. It is possible to reduce variations in strength of the whisker-reinforced metal-based composite material and obtain a high-performance composite material having uniform strength.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a defibration process of aluminum borate whiskers.

FIG. 2 is a longitudinal sectional view showing a molded body of aluminum borate whiskers housed in a case.

FIG. 3 is a vertical cross-sectional view showing a high-pressure casting process performed by using the aluminum borate whisker molded body shown in FIG.

FIG. 4 is a graph showing the fatigue strength of a composite material having three types of aluminum borate whiskers having different Si contents as reinforcements.

FIG. 5 is a graph showing flexural strength of composite materials having three types of aluminum borate whiskers having different Si contents as reinforcing materials.

FIG. 6 is a graph showing the relationship between the volume ratio of aluminum borate whiskers and the bending strength of the composite material.

[Explanation of symbols]

 10 ... Aluminum borate whisker 12 ... Distilled water 18 ... Case 20 ... Molded body 22 ... High-pressure casting device 24 ... Mold 26 ... Al alloy melt 28 ... Plunger 30 ... Knockout pin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hatamoto Shikoku Kasei Kogyo Co., Ltd. 1 147 Minatomachi, Marugame City, Kagawa Prefecture

Claims (2)

[Claims] 1. An aluminum borate whisker having a Si content of 150 ppm or less. 2. A metal-based composite material comprising aluminum borate whiskers having a Si content of 150 ppm or less as a reinforcing material and a light alloy as a matrix.